Robert Plath, an airline pilot, is generally credited with inventing the modern style rolling suitcase. Plath is the inventor of U.S. Pat. No. 4,995,487, which discloses a luggage assembly comprising a suitcase having integrally connected thereto a laterally extendable handle at its upper end and a wheel assembly (usually a pair of wheels) at its lower end. To effect transport, the handle is moved from a lowered, compact, position to a raised position and the suitcase is tilted from an upright standing position to a canted position in which it is supported solely by its wheels and rolled by pulling said handle. An attachment allows for additional luggage items to be carried by the assembly and transported in a fully balanced manner. This type of rolling suitcase is sold, e.g., under the trademark Rollaboard® by Travelpro International, Inc.
In a variation of this concept, so-called “spinner” suitcases include four wheels at the lower (usually smaller) end. Spinner suitcases are designed for the four wheels to remain level, in contact with the ground or floor and be free spinning, not to be tilted and rolled like two wheeled rolling suitcases.
Rolling luggage is convenient if one is using only a single suitcase or one rolling suitcase and a smaller bag, e.g., a laptop case, that can be carried on top of and attached to the rolling suitcase. However, rolling suitcases become inconvenient when one is traveling with two or more larger suitcases.
Various proposals have been made for combination rolling carts and suitcases. For example, U.S. Pat. No. 8,720,656 discloses combination rolling cart and suitcase that includes a base suitcase, an external support frame, a plurality of steel stabilizers, a plurality of permanent adjustable straps and plurality of attachment points where the attachment points receive and removably couple the permanent adjustable straps to secure one or more suitcases across a top portion of the combination rolling cart and suitcase. The combination rolling cart and suitcase also includes a pair of telescoping handles, a telescoping stem, a releasable handle lock, a plurality of omnidirectional casters and a lid releasably fastened to the base suitcase.
In the various combination rolling cart and suitcase proposals, three or four wheels are installed on the large bottom face of the suitcase. However, having the three or four wheels exposed on the bottom face of the suitcase poses problems for stacking the suitcases in modern airline cargo holds. Therefore, a number of such proposals have complicated arrangements for retracting some or all of the wheels within the bottom face of the suitcase. These disadvantages are likely why such proposals have not been commercially popular.